Any issues with ZCB 5.0.18 and ZCS 6.0.3?

Hi, I have searched for awhile and don't feel like I've seen the answer for sure, but I'm hoping I'm not asking a stupid question.

We have ZCS 5.0.18 and ZCB 5.0.18 at the moment, and are planning to upgrade the mail servers to ZCS 6.0.3 in January. We have a test server, but I can't really test the Blackberry server ahead of time, so I'm just looking for confirmation/assurance that this transition should go smoothly on the Blackberry end. Has anyone done this? Any roadbumps to report?

As far as I can tell, ZCB 5.0.19 is the latest available, period, and I'm wondering if I should upgrade the ZCB from 5.0.18 to 5.0.19 BEFORE the ZCS upgrade, or at roughly the same time, i.e., just after the ZCS upgrade has proven to work fine?

Just curious if the calendar syncing problem is still happening for you. We're jumping to 6.0.4 in a few weeks and have quite a lot of BES users that will complain if calendar sync starts having problems.

I haven't resolved it yet, but it only affects two of ten users. I have tried to delete one of the two users from the BES, add him again, re-activate. Calendar syncs, but the device does not recieve appointment invitations. Will look into this in January...
I will try to kill all data from the handheld and then repeat the procedure (delete user, add user, activate) and see what happens.

I am planning to upgrade our zimbra server 5.0.18 + ZCB to the latest 6.0.5. I was wondering if you've managed to resolve your calendar problems? My users rely on the calendar and would have a lot of issues if it starts to have issues.